Fans never attended BYU. My family and friends stretch from St George to Moab to SLC to Logan. The vast majority of the BYU fans among them never attended BYU. I get that the school atrendance plays a role to a degree however the vast majority of "Ute fans" and "BYU fans" in the state of Utah never attended either school.
The majority of the time attended SUU, Dixie, USU, Weber etc... So while the school thing plays a role it's much smaller than what you give it credit for in the state of Utah.